If an electrical discharge machine is operated for a long period of time, various expendable parts of the electrical discharge machine wear away and suffer deterioration in performance, thus possibly entailing a trouble which disables operation, as well as reduction in machining accuracy and machining speed. Accordingly, the exhausted parts must be replaced with new ones. Conventionally, an operator determines whether the life of each expendable part has terminated, on the basis of visual observation or experience. It is difficult, therefore, to replace each part at an appropriate time. If the time for the part replacement is too early, the operation cost of the electrical discharge machine increases. If the time is too late, on the other hand, the aforesaid awkward situation is entailed.
Further, the electrical discharge machine supplies a machining fluid to predetermined regions, such as the gap between a workpiece and an electrode, a workpiece stand, etc., by injection, thereby removing heat and machining chips produced during electrical discharge machining. If the machining fluid storage level in a machining fluid reservoir extraordinarily drops due to anything unusual in a machining fluid supplying device or the like, however, the machining fluid cannot be normally supplied, so that the operation of the electrical discharge machine is hindered.